Temperature Controller using PIC Microcontroller and TRAIC phase angle control.

1. A Project Presentation by-
SUPRIYA GORAI (10705515049)
TATINI MANDAL (10705515052)
ABHASH CHANDRA SOURAV (10705515001)
AAKASH KUMAR (10705515053)
TEMPERATURE CONTROLLER USING
PIC MICROCONTROLLER

2. CIRCUIT DIAGRAM

3. WORKING PRINCIPLE
The working principle of this programmable ac power control
using PIC microcontroller device is very simple, its works on the
principle of firing angle change of thyristor. The output power can
be checked with the brightness or intensity of the lamp. AC power
could be changed from 1% to 100% when ac power is changed
then the brightness of output lamp is automatically changed.
Zero crossing detection is very important, especially in power
control circuits employing thyristors.The PIC 16F877A detects the
zero crossing using the RB0/INT external interrupt function. In
phase angle control, a gate pulse is sent to the triac. This is
sent at a time between one zero crossing and the next. After
a certain time, the gating signal is given to the triac and it
turns on. The triac then stays on until the current through it
becomes zero (natural line commutation). How long the triac
is on, is, in turn, determined by the delay time between the
zero-crossing and the applying of the triac gating signal.

4. PIC DEVELOPMENT BOARD
With this board we can develop and prototype with PIC (40 pin)
microcontrollers. The board have User buttons and status LEDs. The
bridge rectifire allow this board to be powered with both AC and DC
power supply adapters.
Features
1. PIC Development Board for Microchip any 40 PIN PIC Series like.
16FXXX, 18FXXX (EX. 16F877A - 40 PIN).
2. ICSP Socket for Programming through PICKIT2 or PICKIT3
3. On board Regulated Power Supply 5v,12v supplies
4. Easy to test with Burg Connecters wires
5. An RS232 Serial Port
6. 7 Segment Multiplexed Display
7. DC Power Supply Connector(12v Ac or Dc)
8. READY INTERFACE For LCD display 2linex6Character
9. 24Cxx (I2C) (EEPROM)
10. RTC (DS1307)
11. 4 LED array
13. 4 Interrupt Switches
14. ADC Interface Support

5. PIC16F877A MICROCONTROLLER

6. PICKIT 2 PROGRAMMER
PICkit 2 Debug Express allows in-circuit debugging on selected
PICmicro microcontroller units (MCUs). In-circuit debugging allows the
designer to run, examine, and modify the program while the PICmicro
MCU is embedded in the hardware, thereby assisting the designer in
debugging the firmware and hardware together. Debug Express interacts
with MPLAB IDE software.

7. K- TYPE THERMOCOUPLE
Features
Working voltage: DC 5V
Operating Current: 50mA
Temperature measuring range: -2°C to 800 °C [Test
procedure for 2-800 °C]
Temperature measurement accuracy: ± 1.5 °C
Temperature resolution: 0.25 °C
The output mode: SPI digital signal
Storage temperature: -20 ~ 80 °C
Type-K Thermocouple (Chromel/Alumel) Type K
thermocouples usually work in most applications as they are
nickel based and exhibit good corrosion resistance. It is the most
common sensor calibration type providing the widest operating
temperature range.

8. 16x2 LCD DISPLAY
LCD (Liquid Crystal Display) screen is an
electronic display module and find a wide range of
applications. A 16x2 LCD display is very basic module and is
very commonly used in various devices and circuits. These
modules are preferred over seven segments and other multi
segment LEDs.

9. Power Supply
The 220V- 50Hz ac voltage is stepped down using a 12-0-12V
transformer and then fed to a bridge rectifier. The output will
contain dc components as well as ac components. A filter
capacitor is used to produce a pure dc supply and is applied to a
7805 voltage regulator IC. Thus the circuit will produce a 5V
supply to power up the other circuits and the PIC
microcontroller,

10. Zero Crossing Detector
A Zero Crossing Detector Circuit is used to track the changing in the sine
waveform from positive to negative or vice versa while it crosses Zero voltage.
The supply from ac source is rectified using a bridge rectifier and then applied
to an optocoupler 4N25. The optocoupler have an led which when turned ON, it
activates the transistor. When the transistor is turned on, the 5V supply passes to
the ground. In other words, during the zero point of sine wave, a HIGH output is
produced which will be fed to the microcontroller.

11. TRIAC Firing Angle Control Circuit
TRIAC, from triode for alternating current, is a generic trademark for a three
terminal electronic component that conducts current in either direction when
triggered. The triac acts as a switch which allows AC supply to pass through it
when a gate signal is applied. Here the microcontroller generates PWM signal
that is applied to the gate terminal of traic BT136 using triac driven optocoupler
MOC3021. The optocoupler not only drives the triac but also isolates the
microcontroller from the AC circuitry.

12. Waveforms

13. .
Thermocouple Compensation
The Thermocouple voltage difference is amplified with an
LM358 in non-inverting amplifier configuration. It is
configured for significant gain in order to get the µV
reading into the 0-5V scale readable with an
microcontroller analog input.
The second op amp in the LM358 is used to buffer the
reading - really unnecessary in this configuration as the
microcontroller analog input presents a fairly high
impedence load.

14. Applications
• Temperature controllers are used in ovens and in heat-treating applications
within furnaces, ceramic kilns, boilers, and heat exchangers.
• Temperature control in the plastics industry is common on portable chillers,
hoppers and dryers
• Temperature controllers are used in the healthcare industry to increase the
accuracy of temperature control. Common equipment using temperature
controllers includes laboratory and test equipment, autoclaves, incubators,
refrigeration equipment.
• Common food processing applications involving temperature controllers
include brewing, blending, sterilization, and cooking and baking ovens.